Machine for cutting screw-threads upon screws.



W. AVERY.

MAUHINE FOR-CUTTING SCREW THREADS UPON SGREWS. APPLICATION FILED FEB. 27', 1909.

fi g Patented. Feb. 1, mm.

9 BKEBTS-SHEET 1.

lkvarafiarr W. AVERY.

MACHINE FOR GUTTING SCREW THREADS UPON SCREWS. APPLICATION FILED r1211. 27, 1909.

948,200" Patented Feb. 1, 1910.

H0. Kant/flue Wmwwcw: 15x06 72?)": g i 9? 26. in Qrr/v w. AVERY. MACHINE FOR swarms scnnw THREADS uron scREws. APPLIGATION IILED FEB. 2'7, 1909. 948111 Patented Feb. 1, 1910.

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W. AVJElRY MACHINE FOR CUTTING SCREW THREADS UPON SUREWfi. APPLICATION FILED FEB. 21, 1909.

Patented Feb. 1, 19m.

9 SHEETS-MEET 4.

ANDREW. s. GRAHAM c0" Punw-umoumr uwi WASHMGTCN. BY 1:,

W. AVERY.

MACHINE r03 CUTTING SCREW THREADS UPON SCREWS. APPLIOATION FILED 1'33. 27, 1909.

Patented Feb. 11, 1910.

9 SHEETS-SHEET 5.

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munew. a. GRAHAM co. PMOTO L\THOGRAPHERR. WAEHINGTON. u. c.

W. AVERY. MACHINE FOB CUTTING SCREW THREADS UPON SCREWS.

APPLICATION FILED FEB. 27, 1909.

Patented Feb 9 SHEETS-*BHBET 6.

, a W. AVERY. MACHINE FOR. CUTTING SGRBW THREADS UPON SCREWS.

APPLIOA'IION FILED FEB. 27, 1909.

Patented Feb. 11, 1910.

9 SHEETS-SHEET 7.

fizaazizn' W. AVERY.

MACHINE FOR GUTTING SCREW THREADS UPON SCREWS.

APPLICATION FILED FEB. 27, 1909 9 SHEETS-SHEET B.

Patented Feb. 1,1910;

W. AVERY.

MACHINE FOR CUTTING SCREW THREADS UPON SCREWS.- APPLIUATION FILED FEB. 27, 1909.

948,200., Patented Fell 1,1910.

9 SHEETS-SHEET 9 SATES. 11*

ll lb.

WILLIAM AVERY, or RICHMOND, ENGLAND.

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To all whom it may concern:

Be it known that I, YVILLIAM AvnRY, a subject of the King of Great Britain, residing at Richmond, in the county of Surrey, England, engineer, have invented certain new and useful Improvements in Machines for Cutting Screw-Threads upon Screws, and of which the following is a specification.

This invention refers to an improved ma- 1 chine for automatically cutting the screwthreads upon screws, such as wood screws, which are to be tapered toward the points, and the said machine hereafter described is constructed to take a blank (consisting of a metal shank having a head) and to pass the head of the blank between rotating gripping jaws which close and grip the shank near the head. The rotating blank is then sub jected to the action of a tool which turns its end to a point. Then a cutting tool is brought against the shank at a short distance from the jaws and traversed to the end of the shank, the motion of the cutting tool being at a slight angle to the axis of the blank to produce a tapering core. Upon the cutter approaching the pointed end of the blank it is advanced more rapidly toward the axis to cut the thread upon the tapering end, and at the same time the cutting tool is accelerated in one of its traverse motions as it nears the point of the blank and is retarded in its next traverse motion, so as to form the thread upon the pointed end of a pitch and thickness equal and corresponding to the thread upon the cylindrical portion of the shank. After the cutting tool has been traversed in its cutting action along the shank and has reached the pointed end it is caused to recede and return to its starting point and then to again advance and make the next cutting traverse and so on; and when the thread has been completely formed taking off or thief fingers seize the finished screw and carry it away.

All .the working parts in the machine according to this invention, are, as will be observed by the following description, arranged above the blank which is being operated upon, and this is an important feature because the oil used in lubrication is not then washed out of the bearings by the water used for the cutter, and the shavings, swarf, and other matters fall clear and not upon the working parts, and thus this ma- Specification of Letters Patent.

Application filed February 2'7, 1909.

chine is rendered less liable to derangement.

Patented l eb. ll, will).

Serial No. 480,451.

Further I desire to draw attention to several other salient features which characterize the machine constructed according to my invention.

A member or back-die is provided ar ranged to be capable only of receiving traverse motions in the direction of the length of a groove formed 1n the said back-die, and

so located that the axis of the shank of a screw blank carried in such groove is coaxial with the axis of rotation of gripping jaws carried by a revoluble spindle, through which jaws the head of the blank is passed by the rectilinear sliding motion of the said back-die in the direction of the axis of the screw blank. The rotating jaws having seized the blank so placed within their grip, the shank of the blank shares the rotation of said jaws and is at the same time supported, by the now stationary back-die, against lateral thrust of the cutting tool which is brought into operation for forming the screw-thread.

In the apparatus according to this invention it will be noted the longitudinal member forming the back-die is not revoluble and although it is used to support the shank during the cutting operation, it does not form a medium by which the blank is held. The said member or back-die in the present invention is only given longitudinal traverse motions to carry the blank endwise into the said revolving gripping jaws, which will then themselves hold and rotate the blank, while the said back-die merely effects the ofiice of supporting the blank during the turning and screw-cutting operations, and so prevents the shank being bent or broken.

In my said invention a slide is employed carried in the framework and having motions in the direction of the axis. of the screw blank; this slide which carries the grooved back-die before mentioned also carries feed mechanism by which the blank is taken from stationary guide rails and transferred to the groove of the said back-die, and the said slide further carries a rock-shaft upon which is mounted a cutter-carrying arm, through the medium of which the blank is pointed prior to the screw-cutting operation.

The machine about to be described is fitted with a longitudinal shaft having fixed thereto a tool carrying arm, and the longitudinal shaft is slid endwise during the cutting operation by the action of a cam and given its return motion by means of a spring, and the same spring is used torsionally to carry the cutter away from the work by rocking the longitudinal shaft about its axis, which mechanism has already been suggested in screw-cutting machines, but in the present machine the longitudinal shaft having the tool-carrying arm is located parallel with but above the screw to be cut, and moreover the cam by which the longitudinal shaft receives its endwise movement in one direction, acts upon a part connected to the tool-shaft and projecting therefrom.

In screw-cutting machines it has been proposed to advance the cutter radially toward the work by a cam and lever action, and a wedge or inclined plane operated by a cam has been proposed to be employed to so regulate the cutter as to produce the required taper of the screw-thread. Now in the machine about to be described a regular cam of volute character is employed to which is communicated one revolution during the several traverse motions of the cutter necessary to complete the formation of the thread, and this cam acts to vary the position of a rocking member, which I will term the first rocking member, and the latter controls the position of a second rocking member carrying a mold bar. Through the medium of this mold bar the angular position of the longitudinal shaft carrying the tool-carrying arm is controlled and regulated, and means are provided for regulating the position of the second rocking member carrying the mold bar irrespective of the position of the first rocking member, which latter is operated and controlled by toggle mechanism governed by the regular volute cam before mentioned.

In the construction of the machine hereafter described, the first rocking member operates the second through the medium of movable tappet pieces, which latter, when in one position carry the screw-cutting tool up to its work on the blank, and when in another position allow the screw-cutting tool to fall away from the blank preparatory to its return motion.

The improved mechanism hereafter described by which the acceleration and retardation of the traverse of the cutting tool is effected as it nears the point of the blank, is an important feature of this invention.

In screw-cutting. machines it has been proposed to employ a cam-actuated wedge to act upon a shaft, through the medium of which the cutter-carrying shaft is given such endwise motion that at one time one side of the cutter or chaser is brought into action against the blank, and at another time the other side of the chaser is brought into action against the blank, so that the chaser alternately acts on one side and then on the other. With the mechanism according to this invention the tool-carrying shaft is directly operated upon and the cutter is accelerated in its speed at one traverse motion during its cutting operation as it nears the point of the blank and at its next traverse motion it is retarded in speed.

The machine also comprises other features and combinations of mechanism as hereafter described.

An example of construction of the machine according to this invention, will now be described with reference to the accompanying drawings.

Figure l is a front elevation of my improved machine for automatically and mechanically cutting or forming screw-threads upon screws, particularly wood screws. Fig. 2 is a plan view of the same. Fig. 3 is an end elevation looking from the left-hand of Fig. 1, showing certain parts of the mechanism, and particularly the feed device and the device for taking the finished screws from the gripping jaws and other parts hereafter referred to. Fig. 4: is a sectional end elevation looking from the left-hand of Fig. 2 and showing the cam for reciprocating the slide, a portion of the mechanism for controlling the screw-cutting tool, and other parts. Fig. 5 is a sectional end view illustrating mechanism for controlling the screw-cutting arm, and Fig. 6 is a front elevation of a mold bar hereafter described. Fig. 7 is a longitudinal vertical section showing the gripping jaws, the means for operating the same, and the spindle shaft by which they are carried. Fig. 8 is a horizontal section of a portion of the tool-carrying shaft showing part of the mechanism for accelerating and retarding the travel of the screw-cutting tool. Fig. 9 is a vertical cross section of the parts shown at Fig. 8 taken about the line X Y of the latter figure. Fig. 10 shows in plan view the cam for reciprocating the slide. Fig. 11 is a plan view of the cam for operating the accelerating and retarding mechanism, and Fig. 12 shows the same cam with its .movable part in another position. Fig. 13 is an elevation of a screw blank as supplied to the machine. Fig. 1a is a similar view of the blank after being subjected to the first operation, and Fig. 15 shows the finished product.

Referring to the accompanying drawings, the machine comprises a stationary frameworr 1 from and by which the various mechanisms and moving parts are supported; and mounted in bearings 2, carried by this framework 1, is a revoluble spindle 3 which carries the jaws l, hereafter described, by which the blank is gripped and revolved during the threading operation. The spindle 3 is formed with a pulley surface 5 which is continuously driven by a belt from any prime mover.

The spindle 3 carries a bevel pinion 6 shown by dotted lines at Figs. 1 and 2,

which gears with a bevel pinion 7 shown by dotted lines at Fig. 2, mounted upon a shaft 8 carried in suitable bearings from the framework 1, and the said shaft 8 at its opposite end has a pinion 9 gearing with a wheel 10, the shaft of which carries a pinion 11 gearing with a spur wheel 12 (Figs. 1 and 2) fixed on a shaft 13 (Fig. 2) carried in bearings and extending transversely across the machine, this shaft 13 being what I term the fast motion cam shaft and which revolves once during the motions of the thread cutting tool in cutting the thread and returning prior to again effecting a cutting movement. At its opposite end the shaft'13 is fitted with a pinion 14 (Fig. 2) driving, through an idle pinion, a countershaft 15, which by bevel gear 16, drives a main cam shaft 17, (Fig. 2) extending longitudinally and parallel with the axis of the jaw spindle 3.

The screw blanks are fed in between two guide rails 18, so that the said blanks are held suspended by their heads and these guide rails 18 are then curved in a somewhat helical manner downward, so that they arrive in such a position that the blanks are held with their axes horizontal. The lower portion of these guide rails 18 is shown at Figs. 2 and 3 and their lower ends are fixed by a bolt 19 (Fig. 2) to a projecting portion of the framework 1.

Referring to Fig. 3 it will be observed that the lowermost blank 20 in the guide rail is retained by an arm 21, which is pivoted to lugs extending from one of the guide rails 18 and is retained normally in the position shown at Fig. 3 by a spring 22 extending between an arm 23 on the spindle of the arm 21 and a part of the guide rail; the arm 21 is bifurcated, and each member of the bifurcation is formed with a claw (Fig. 3) and the spring 22 which governs the arm 21 is of a delicate character, so that the weight of the blanks in the lower part of the guide rails 18 is sufficient to force one of the blanks, such as 20, into the grip of the claws at the ends of the arm 21.

The lower end of the lowermost guide rail. 18 abuts upon, and its surface is flush with, the inclined face of a head 24, which carries and embraces the greater circumference of a cylinder 25 made with several longitudinal grooves, and the cylinder which I term the back-dieis so placed that one of such grooves is located on its exposed surface, and it is into this groove that the shank of the blank is to be carried and held by a feeding finger while the said blank, together with the back-die 25, is given a longitudinal motion to carry its head through the gripping jaws of the spindle 3. To effect this, a slide 26 is provided capable of being slid in longitudinal guides 27 and this slide 26 carries, by means of a bracket 28, Fig. 3

an arm 29 fulcrumed at 30; the opposite end of the arm 29 has a horizontally extending bar 31 (Fig. 2) bored to form a sleeve bearing for the pivot pin of a finger 32 held down in a position shown at Fig. 3 by a light spring 33 (Fig. 2) extending between a pin 34 (Fig. 1) on the arm 29 and a radial pin on the axis or spindle of the finger 32. The said finger 32 is capable of passing, as the arm 29 is rocked, between the bifurcated members of the arm 21, so that the somewhat forked end of the finger 32 can pass over the shank of the blank 20 held by the jaws of the arm 21, and take that shank out of the grip of the said jaws, and then as the arm 29 is rocked, it carries (as shown at Fig. 3), the blank down the inclined surface of the head 24 into the groove of the back-die 25, where it is still held by the clawlike end of the finger 32. To effect this mo tion, the arm 29 carries a longitudinally ex tending rubbing piece 35, Fig. 3, andthe said il-I'IH 29 is held up by a helical spring 36, so that its rubbing piece 35 contacts with a surface cam 37 which I term the feed cam and which is mounted upon the slow main cam shaft 17.

The gripping jaws 4 carried within the spindle 3 may be of any desired or well known construction. As shown at Fig. 7, the jaws consist of two levers 4 pivoted at 38 in the shell forming the head of the spindle 3, and carry, on their rear ends, rollers which are acted upon by a wedge 39, so that when the wedge is forced toward the jaws, the gripping ends of the latter are closed. The wedge has a bearing for its sliding motion within the spindle 3, and is fixed to a sliding rod 40 extending through the rear end of the spindle 3, a spring 41 on the rod 40 within the spindle tending to force the wedge 39 forwardly to close the jaws 4, while when the wedge is withdrawn, the said jaws are opened by a spring 42.

The rod 40, at its rear projecting end, is fitted with a trunnioned yoke 43 (Figs. 1 and 2) which is engaged with one arm of a bell crank lever 44 (Fig. 1), the other arm of which, by a rod 45, is connected to one arm of a two-armed lever 46 Fig. 1, (also shown in dotted lines at Fig. 4) fulcrumed on a stud 47 on the framework, the other arm of the lever 46 being acted upon by a cam 48 on the main cam shaft 17, so that at proper times the jaw-opening cam 48 operates to draw out the rod 40 against the action of the spring 41 thereon, and so permits the jaws to open by the action of the spring 42, while at other times the cam 48 permits the spring 41 of the rod 40 to act and close the jaws to grip the blank.

The slide 26 receives rectilinear reciproeating motions by means of a cam 49, (Figs. 2 and 4) acting upon a stud 5O fixed to the said slide. The approximate formation of the cam 49 on the shaft 17 is also illustrated at Fig. 10, from which view it will be readily seen that the stud 50 is given a positive traverse motion at each revolution of the cam 49.

It will now be understood that upon a blank being carried and held in the groove of the back-die 25 with its head and a portion of its shank projecting beyond the right hand end of the said back-die, the slide 26 receives a motion toward the jaws 4 by means of the slide cam 49 and carries with it the arm 29 and the head 24 with the backdie 25, the rubbing piece 35 being of sufficient length to permit of this movement without it leaving the cam surface of the cam 37, and so the head of the blank is introduced between the jaws 4, and the jaws are allowed to close upon it by the cam 48 releasing the rod 40; then the arm 29 is rocked, and the finger 32 leaves the blank (which it has fed and held in the groove of the back-die until the seizure of the blank by the jaws) and proceeds to collect another blank. The blank having been thus gripped by the revolving jaws, is so revolved in the groove of, the back-die, which serves as a support for the shank of the blank during the screw-cutting operations.

Carried in a sleeve extension 51 (Fig. 3) on the slide 26 is a rock-shaft 52, on the inner end of which is a lever 53 (Fig. 2) connected, by a connecting rod 54, to the arm of a lever 55, rocking about a stud axle 56 projecting from the framework; the connecting rod 54 is fitted with a spring 57 (Fig. 3), and its ends are connected by ball joints to the levers 55 and 53, so as to permit of the lateral motion of the slide 26. The lever 55 carries a rubbing piece 58 (Fig. 3) which bears upon a cam 59 mounted on the main cam shaft 17.

On the opposite end of the rock-shaft 52 is a tool-carrying arm 60 (see Figs. 1, 2 and 3) carrying a cutter 61, the office of which is to act upon the end of the screw blank as hereafter described, to point the same as at Fig. 14, so that when the blank is gripped in the aws 4, the pointer cam 59 acts upon the lever 55, rocks the shaft 52, and brings the cutter carrier 60, with its cutter 61, into contact with the end of the shank of the blank, and so forms the point, after which the cutter-carrying arm 60 resumes its normal position shown at Fig. 1.

The pointing tool-carrier 60 is fitted with a regulating screw 62 (Figs. 1, 2 and 3), which, as the cutter 61 completes its pointing out, bears up against the end of the back die 25 and forms a stop to limit the extent of the cut.

Mounted in the framework, above the axis of the revoluble jaw-carrying spindle 3, is a tool-carrying shaft 63 (Fig. 1), which is formed with a loop to allow of the passage of the cam shaft 13 as shown by dotted lines at Fig. 1. The tool shaft 63 is capable of two motions viz: of rocking about its axis and of an endwise sliding motion, being impelled endwise at proper times and at proper speeds as hereafter described, in a direction from right to left of Fig. 1, and being caused, when free, to move from left to right by means of a spring 64, and at what I term its forward end the tool shaft 63 has mounted upon it a tool-carrying arm 65 (Figs. 1, 2 and 3) which carries the cutter 66 by which the screw-thread is formed, and the tool-shaft 63 receives its forward sliding motions against the action of the springs 64 by means of a volute pitch cam 67 which acts upon a bearing surface 68 (see also Fig. 8) carried from a sleeve 69 on the said shaft 63.

It has been stated that the tool shaft 63 receives a motion from right to left of Fig. 2 by the action of a volute cam 67, during which the cutter 66 effects its cutting action on the blank, and then the cutter is caused to retreat from the blank, and the tool-carrying shaft 63 is allowed a rapid return by means of the spring 64 (Fig. l), and it is now necessary to describe the means which I adopt for rocking the tool-shaft 63 about its axis to bring the cutting tool 66 away from and to advance it toward the blank.

Referring to Fig. 5, the tool-shaft 63 carries a rearwardly extending arm 70, the head of which carries an adjustable stud 71. In order to act upon this stud, I mount upon a shaft 72 (Figs. 2 and 5) carried from the framework at the rear of the machine, a regulating frame 73 capable of rocking motions upon the shaft 72, and having two forwardly extending arms united toward their forward ends by a bar 74. This frame 73 is connected by a pair of links 75, which are pivoted at one end at 76 to lugs extending from and below the bar 74, and at the other end are pivoted at 77 to lugs projecting from a sleeve 78 loosely mounted on the main cam shaft 17.

The sleeve 78 is formed with a lug 79 from which a connecting rod 80 extends, the oppo site end of the latter rod being adjustably fixed in the slot of a curved arm 81, fixed upon a shaft 82 (Figs. 4 and carried from the framework, and upon the said shaft 82 is fixed a lever 83, the outer end of which is held by a spring 84 (Fig. 5) in contact with. a cam 85 upon the cam shaft 17 (see also Fig. 2). By this mechanism, the lever 83 operated by the cam 85, rocks the sleeve 78 upon the shaft 17, and operates the toggle connect-ion of which. the sleeve itself forms one member, while the links 75 form the other member, and thus the frame 73 receives its rocking motions about the shaft 72.

The cam 85 Fig. 5 revolves once during the operations effected by the machine upon the blank, and while the volute portion of the cam (which revolves in the direction of the arrow Fig. 5) is acting upon the rubbing piece of the lever 83 the screw cutting tool (36 receives the necessary number of reciprocationsby the sliding movement of the shaft 63to commence and complete the cutting of the screw thread. The formation of the cam 85 is such that during the reciprocations of the screw-cutting tool 66 the toggle mechanism 7 5, 7 8 is gradually straightened out and consequently gradually turns the frame 73 upward about its fulcrum 7 2 and thus gives the necessary advance feed of the cutting tool to its Work.

Loosely mounted upon the shaft 7 2 (Figs.

2 and 5) is an inner frame 86 having two arms which pass within and parallel to the outer frame 73, and these arms of the inner frame 86 carry between their ends a longitudinal bar 87, which I term a mold bar. The mold bar 87 is separately illustrated in front elevation at Fig. 6 in order to show the configuration of its upper surface. This upper surface of the mold bar 87 is formed for a considerable part of its length slightly inclined to the horizontal plane, and then rises in a curve until it joins an upper horizontal surface 88, and the mold bar 87 is capable of slight rocking motions about its axis in the arms of the inner frame 86. It is upon the shaped upper surface of this mold bar that the stud 71 of the cut-controlling arm 70 bears the said stud being held thereto because the tool-shaft 63 (Fig. 5) always has a force acting upon it tending to turn it in the direction of the arrow in that figure, and consequently to force the stud 71 carried by the arm 70 into contact with the surface of the mold bar, and the shaft 63 is acted upon to this end by the spring (34 (Fig. 1) located on the end of the tool shaft 63, which spring, as has been before stated, tends to draw the shaft 63, when free, from left to right, and also is mounted so that it exerts the desired torsional force to cause the stud 71 of the cutcontrolling arm into contact with the said surface ,of the mold bar 87. The mold bar 37 is capable of the slight free rocking action about its axis as previously stated (see Fig. 6) in. order that the under-surface of the stud 71 shall always have a firm bearing upon the formed surface of the said bar.

Beneath the mold bar 87 and on the outer sides of the arms of the inner frame 86,

the arms of the inner frame 86, and so: bring and keep the frame 86 in an upper pos1t1on relatively to the frame 73, while at other times by rocking the shaft 90, the tappet pieces 91 can be brought away and the inner frame 36 can then descend relatively to the arms of the frame 73; by this action the mold bar 87 can be altered as re gards its elevation irrespective of the position of the outer frame 73, which latter outer frame it will be remembered is governed by the toggle mechanism and by the cam 85.

I11 order to operate the rock-shaft 90 of the outer frame 73, the said shaft projects beyond the outer frame and is fitted with a crank 92 to which one end of a connecting rod 93 (Figs. 2 and 5) is pivoted, while the opposite end of the said connecting rod 93 is pivoted at 9% (Fig. l) to alever 95 fulcrumed to the frame at 96 (Fig. a) the lever 95 at its upper end being provided with a laterally extending pin 97 which pin bears against the face of a cam 98, which I term the relief cam.

The pin 97 is held up to the face of the relief cam 98by means of a spring acting on the lever 95 (not illustrated in the drawings), and the face of the said relief cam is formed by a flange, which at one part shown at Fig. 4 is cut away, so that unless otherwise restrained, the pin 97 would pass through the gap in the cam flange and allow the lever 95 to rock over beyond that face of the cam upon which its pin 97 normally bears. To govern this motion the lever 95 is provided with a pin 99 which projects laterally, and which at times bears upon theperiphery of the cam -19 which operates the reciprocating slide 26, that is, it bears upon the periphery of the slide cam.

The relief cam 98 and the slide cam 49 so co-act upon the lever 95, that the pin 97 passes through the gap in the flange of the relief cam to about the dotted line 100 (Fig. at) during the return of the cutting tool, and it is prevented passing farther through the gap of the cam by reason of the pin 99 bearing upon the periphery of the cam 49. During however, the feeding of the blank to the gripping jaws and the pointing or sha ing of the end of the blank, the pin 97 o the lever 95 is allowed, by the shaping of the periphery of the cam 49, to pass entirely through the gap of the cam 98.

hen the pin 97 is allowed to pass through the gap of the cam 98 as far as the dotted line 100, Fig. 4:, the connecting rod 93 (Fig. 2) will receive a forward motion sufficient to rock the rock-shaft 90 (Fig. 5) and so remove the tappet pieces 91 from beneath the studs 89 of the frame 86, and consequently the frame 86 immediately 'descends, followed by the stud 71 and the arm 70, and the cutting tool 66 is removed from contact with the blank, and it is in this position of the frame 86 and the tappets 91 in which the tool is returned from the pointed end of the blank to the point at which the cut of the screw-thread commences.

When the pin 97 is allowed to pass entirely through the gap of the cam 98, not only are the tappet pieces 91 thrown out of action, but also the forward end of the connecting rod 98 (Fig. 2) is carried so far forward that it contacts with a trigger 101 (Figs. 2 and 4) which is normally held in the position shown by a suitable spring, and the spindle of the trigger 101which is carried in a bearing bracket 102 mounted on the slide 26-has a tooth 103 which is capable of being brought into the path of a projection 10st extending from the sleeve 69 on the tool shaft 63 (Figs. 1, 2 and 4) and the office of this tooth 103 is to be brought behind the projection 104, as shown at Fig. 2, at the time that the tool carrying shaft 63 is in its most forward posit-ion, so as to hold it in that position while the blank is being fed into the gripping jaws t and while the point of the blank is being turned.

I will now describe the mechanism by which the cutter 66 is caused to accelerate its traverse motion as it nears the point of the blank at one time, and at its next traverse cutting motion it is retarded in its speed, so that by these variations of speed of travel, the thread is reduced at the pointed end of the screw.

Within the sleeve 69 (see particularly Figs. 2, 8 and 9) the tool shaft 63 has a recess formed in it, and farther forward of that recess the shaft 63 has a bore extending to the cutter end, and in the bore is located a rod 105, which bears against an adjustment screw 106 tapped into the bore of the shaft 63, while the opposite end of the rod 105 extends into the recess 107 in the shaft 63. Carried by the sleeve 69 is a lever 108 (Figs. 8 and 9), fulcrumed at 109 and capable of acting against the end of the rod 105, while the opposite end of the lever 108 can be acted upon by a sliding plunger 110 carried by the sleeve 69. It must be realized that the sleeve 69 is loose on the. shaft 63, and the sleeve is subject to a pressure by means of the volute cam 67, acting upon the rubbing piece 68 to force the shaft from right to left during the screw-cutting operation in the direction of the arrow (Fig. 8) that is, during the time the cutter 66 is acting to cut the thread on the blank. Now so long as the plunger 110 (Fig. 8) remains stationary and the lever 108 is maintained thereby in any set position, the sleeve 69 is fixed to the shaft 63 so that any forward movement in the direction of the arrow (Fig. 8) given by the cam 67 is transmitted directly to the shaft 63.

If the plunger 110 is allowed to recede from the end of the lever 108 during the forward movement of the sleeve 69, the lever will turn about its fulcrum 109, and the tool shaft 63 will move through a lesser distance than the sleeve, and therefore the cutter carried by the shaft 63 will be retarded in its traverse. On the other hand, if the plunger 110 is forced inward during the forward movement of the sleeve, the opposite result will take place, viz., the cutter shaft will be accelerated in its traverse.

In order to control the plunger 110 a pendent lever 111 (Figs. 1 and 4-) is fulerunled from the framework 1, and is provided with a horizontally extending rubbing piece 112 against which the end of the plunger 110 bears, and the tail or lower end of the lever 111 is controlled by laterally exteiuling stud 113 on the end of an arm 114- liXcd on a shaft 115 carried in hearings in the framework. The opposite end of the shaft 115 carries an arm 116 (Fig. 1) carrying at its upper end a pin or bowl 117, which is acted upon by a switch cam 118 (Fig. 1) fixed upon the shaft 13, and the latter cam is shown detached in plan view at Figs. 11 and 12.

The cam 118 carries a gate 119 pivoted at 120 and so formed that as the cam 118 revolves from the position shown at Fig. 11, the pin 117 of the lever 116 passes in be tween the gate 119 and the face flange 121 of the cam, and in this movement the gate is rocked on its pivot 120 which turns with some frictional resistance and leaves the gate 119 in the position shown at Fig. 1:2, so that at the next revolution the pin 117 will pass over the face of the gate, while so long as the pin 117 bears against the face liange 121 of the cam, the pin 117 will remain stationary. So long therefore as the pin 117 lies against the face flange of the cam, the plunger 110 will be held stationary, it sliding on the face of the rubbing piece 112, while when the pin 117 passes between the gate and the flange of the earn, the plunger 110 will be allowed to reccde from the lever 108, and the cutting tool will be retarded, while obversely, when the pin 117 passes over the face of the gate 119, the plunger 110 will be forced inward and the cutting tool accelerated in its traverse motion. The thread having been thus out upon the screw, the shaft 63 is retained in its most forward position, that is it is retained in the position shown at Fig. 2 of the drawings, by the tooth 103 passing behind the projection 10st of the sleeve, and then the thief lingers grip the shank of the screw near the jaws, which latter are then opened by the operation of the lever 14 acted upon by the cam 48, and then the thief lingers carry the screw from right to left, and then forwardly when the lingers release the finished screw and it falls into a. suitable receptacle. A convenient mechanism for carrying out this operation consists of an arm 122 (Figs. 1, 2 and 3) fixed on a shaft 123 mounted in hearings in the frame work above the shaft 63, and at the opposite end the shaft 123 has a crank arm 123 shown by dotted lines at Fig. 3, connected by a connecting rod 12 1 to an arm 125 on a shaft 126, which shaft also carries an arm 127 (Figs. 2 and 3) provided with a rubbing piece held in contact with the thief cam 128 (Fig. 2) by means of a spring (not shown) which may be arranged in any convenient manner. The thief cam is shown by dotted lines at Fig. 3.

The shaft 123 (Figs. 2 and is capable of an endwise sliding motion by a tappet action, and to give this motion the cutcontrolling arm has an upstanding projection 129 (Fig. which at times contacts with the shaft 123, compresses a spring 130 on the said shaft 123 (Fig. 2), and advances the finger-carrying arm 122 from right to left. The finger-carrying arm 122 has at its end a sleeve 122 (Fig. 2), and through that sleeve there extends a pivot 133 (Figs. 2 and 3),

and the pivot is free to rock in the sleeve 122*, but the said pivot 133 is given a tend-- ency to turn in the sleeve 122 in the direction of the small arrow (Fig. 3) by means of a torsional spring placed within the sleeve 122 and acting on the said pivot 133, the said spring not being shown in the drawings. At one end of the pivot there is fixed a hooklike part 136 (Figs. 2 and 3) which is caused to contactby means of the torsionally acting spring in the said sleeve with a camlike projection 137 extending from the framework of the machine and consequently stationary. On the opposite projecting end of the pivot 133 there is fixed a finger 131 (Fig. 3), and there is also a finger acting in opposition to the finger 131, z. e. finger 132 but the latter finger is loosely mounted upon the end of the pivot 133.

The ends of the fingers 131 and 132 are suitably formed to receive and hold the shank of a screw, while they are normally held together by any suitable spring such as 13%. The finger 132 has an upper extension carrying a pin 135 (Figs. 2 and 3), which is capable 'of contacting with an upstanding projection 135 extending from the sleeve 122 Beyond this there is a pin 136 (Fig. 2) extending from the arm 122, the ofiice of which is to act as a stop to the hook like part 136 when the latter is freed from the cam'like projection 137. By these means when the arm 122 is turned about the axis 123 in the direction of the longer arrow (Fig. 3) the hook-like part 136 is brought away from the cam-like projection 137 and thereby the pivot 133 is permitted to have angular motion in the sleeve 122 of the arm 122, and this angular motion is communicated to that pivot by the torsionally acting spring before mentioned as being located within the said sleeve 122*. This angular motion of the pivot 133 continues until the hook-like part 136 contacts with the pin 136 (Fig. 2) projecting from the arm 122, and that pin 136 is so located that it stops the angular motion of the pivot 133 by the hook-like part 136 contacting with said pin 136 and coi'isequently stops the angular motion of the fingers carried by the pivot 133 when the said fingers are in the required position to contact with the shank of the screw being held by the gripping jaws. By this contact of the ends of the fingers 131 and 132 with the screw, the fingers are caused to open and receive the shank between them, the finger 131 loosely mounted on the pivot 133 being held closed against the finger 132 by the spring 134: (Fig. Then the jaws 1 having opened, the shaft 123 with its arm 122 is given a lateral motion from right to left, so carrying the screw from the jaws 4, and then the shaft 123 is rocked aboutits axis while the shaft 123 is laterally moved back again, and upon the hook-like part 136 contacting with the cam-like projection 137 as shown at Fig. 3, the fingers 131, 132 are brought into the position shown. In that position the pin 135 on the upstanding part of the finger 132 is in contact with the up standing projection 135 of the sleeve 122, and then as the arm 122 has further angular movement about the axis 123 in opposition to the longer arrow of Fig. 3 and at the same time the hook-like part 136 is in contact with the cam-like projection 137, the finger 131 will be moved away from the finger 132, the latter being retained by its pin 135 contacting with the upstanding projection 135 of the sleeve 122*, and so the fingers being opened, the screw held thereby is allowed to drop.

From the foregoing description the various operations and movements of the machine will have been broadly understood, and it will therefore be unnecessary to de scribe the various movements of the mechanism in great detail. It will however be understood that the blanks supplied to this particular machine are such as is illustrated at Fig. 13 and that these blanks are fed down the guide rails 18 (Figs. 2 and 13) and are taken one by one from the jaws of the arm 21 by the feeding finger, 32, and thereby the shank of the blank to be dealt with is placed in the groove of the back-die 25. While so held in the groove, the back-die 25 is moved up toward. the aws 4 so as to pass the head of the blank through the aws, and the latter then grip the shank of the blank while the feeding finger 32 recedes.

During the period in which the blank is being fed into the gripping aws as just described, the tool shaft 63 is retained in its forward position, (that is with the spring 64 Fig. 1 compressed) by means of the tooth 103 (Fig. 2) having been rocked behind the projecting part 10 1 of the sleeve 69 on the said shaft, whereby the shaft 63 is not acted upon by the volute came 67. The shaft- 63 is still retained in this position by the tooth 103, while the next operation takes place, that is, the tool carried by the arm 60 is brought up to the end of the blank, and thereby the end of the said blank is pointed as shown at Fig. 14. The tooth 103 is then allowed to passaway from the projection 10% on the sleeve 69 by the receding of the end of the connecting rod 93 (Fig. 2), and therefore the shaft 63 immediately slides backward from left to right by means of the spring 64, and the volute cam 67 then commences to act to force the said shaft 63 from right to left. The same movement, that is the receding movement of the connecting rod 93, operates the rock shaft 90 (Fig. 5) of the outer frame 73, and brings up the tappets into the position shown at Fig. 5 thereby suddenly lifting the inner frame 86, rocking the arm 70 and shaft 63, and forcing the cutter 66 up to its work on the blank. As the cutter is traversed along the blank by the sliding motion of the shaft 63, due to the cam 67, the Volute portion of the cam 85 is acting to straighten out the toggle mechanism -78 and thereby at the same time gradually raising the outer frame 73 and the inner frame 86 and consequently giving the necessary advance motion to the cutting tool 66 in conjunction with the inclined surface of the mold bar 87 also acting upon the stud 71 and arm 70.

As the cutter approaches the point of the screw, it must be advanced more rapidly toward the axis of the blank to cut the thread upon the tapering end, and this more rapid advance of the cutter to its work is effected by the stud 71 rising up on the shaped upper surface of the mold bar 87. As the cutter nearly reaches the point of the screw the speed of its traverse motion is accelerated by means of the switch cam 118 (Figs. 11 and 12) operating through the mechanism previously described.

The cutter having arrived at the point of the screw at the end of its first cut, the shaft 90 (Fig. 5) of the frame 73 is rocked through the medium of the cam 85, and the tappet pieces 91 are removed and permit the inner frame 86 to descend, and consequently by the spring 64 (Fig. l) the shaft 68 is rocked and the tool carried away from the blank. At this time the volute pitch cam 67 (Figs. 1 and 2) permits the return of the shaft 68 by its spring 64, the tappet pieces 91 are again brought into the position of Fig. 5, and the next traverse motion of the cutter 66 is effected, but toward the termination of this next traverse motion the cut-ting tool 66 is retarded in its travel through the medium of the switch cam 118. The operations above stated are repeated, until the cutting of the screw is complete, and then the thief fingers 13l132 receive the motions previously described to remove the finished screw from the gripping jaws 4, and the operations are repeated automatically.

\Vhat I claim as my invention and desire to secure by Patent is 1. In a machine for automatically cutting screw threads upon screws the combination with a spindle, means for rotating said spindle, gripping jaws carried thereby, means for opening and closing the latter, a cutter carrying shaftextending parallel with and above the axis of said jaw-carrying spindle, an arm on said cutter-carrying shaft, a cutter carried by said arm for forming the screw thread 011 the screw to be operated upon, and means for operating said cuttercarrying shaft, of a back die movable in the direction of the axis of said gripping jaws and having a longitudinal groove coaxial with the axis of said gripping jaws, means for imparting longitudinal reciprocation. to said back die, feeding mechanism for carry- -ing the shank of a screw blank into and re taining same in said groove until the traverse motion of said backdie places the head of said screw blank into said gripping jaws, and means for removing the said feed mechanism upon said jaws gripping said screw blank, while said back-die remains stationary to support the shank of said screw blank against transverse pressure of the cutting tool carried by said tool-carrying shaft.

2. In a machine for automatically cutting screw threads upon screws, the combination with a spindle, means for rotating said spindle, gripping jaws carried thereby, means for opening and closing said jaws, a shaft extending parallel with said aw-carrying spindle, an arm on said shaft, a cutter car ried by said arm, means for rocking said cutter-carrying shaft about its axis to bring said cutting tool into and out of action, and means for giving said shaft endwise sliding motions, of a slide having a recessed head constructed with an inclined face, means for guiding and reciprocating said slide in the direction of the axis of said jaw-carrying spindle, a back die carried by said head and having a longitudinal groove axial with the axis of said jaw-carrying spindle and exposed beneath said inclined face to receive the shank of a screw blank, stationary guide rails for feeding the blanks terminating adjacent to said inclined face of said head, a pivoted arm carried by said slide, a pivoted spring-pressed finger carried at the free end of said arm and adapted to engage a screw blank, means for operating said arm to cause said finger to feed a blank from said guide rails to said groove of said back die and to retain said blank therein while the slide carries the back die and the finger holding said blank toward the gripping jaws to insert the head of said blank therein, means for closing said jaws to grip said blank, and means whereby said finger is retracted while said back die remains stationary to support the shank of said screw blank against transverse pressure of said cutter, substantially as set forth.

In a machine for automatically cutting screw threads upon screws which are tapered toward the point; the combination with a rotating j aw-carrying spindle, means for opening and closing the aws carried thereby, a cutter-carrying shaft extending parallel with and above the axis of said aw-carrying spindle, means for angularly rocking said shaft about its axis to bring said cutting tool into and out of action, and means for giving said shaft endwise sliding motions; of a member capable of sliding motions parallel with the axis of said j aw-carrying spindle, guides in the framework to carry said sliding member, a back die carried by said sliding member and having a longitudinal groove formed therein the axis of which groove is coaxial with the axis of said rotating jaws, means for reciprocating said sliding member and therewith said back die toward and away from said jaw-carrying spindle, before and after the screw-cutting operation respectively, and for rendering the same stationary in an effective position dur ing said cutting operation, feed mechanism to carry the shank of a screw blank into and for retaining same in said groove of said back-die until said screw blank is carried into and gripped by said gripping jaws, means for removing said feed mechanism durin said cutting operation, a rock shaft, bearings in said sliding member to carry said rock-shaft, a cutter-carrying arm carried by said rock shaft, and means for giving angular motion to said rock shaft to bring said cutter-carryin arm to operate on the end of said blank to 'orm a point thereon, after the removal of said feed mechanism, and while said sliding member is stationary, and means for again rocking said rock shaft to remove said pointing cutter prior to the thread cut ting operation, substantially as set forth.

at. In a machine for automatically cutting screw threads upon screws which are tapered toward the point, the combination with a rotating spindle, gripping jaws carried thereby to grip the blank to be operated upon, a cutter carrying shaft extending parallel with and above the axis of said jawcarrying spindle, an arm on said cutter-carrying shaft, a cutter carried by said arm, means for giving said shaft an end-wise motion to cut the thread on said screw blank carried by said gripping-jaws and means for returnin said shaft prior to the next cutting traverse, and an arm on said shaft for rocking same to bring the cutting tool into and out of action; of a regular cam of volute character, a revoluble shaft to carry said cam and means for giving the said cam one revolution durin the several traverse motions of the cutting tool necessary to complete the formation of the thread, a first rocking member and mechanism operated by said volute cam to rock said first rocking member, a second rocking member, a mold bar carried thereby, a stud 011 the controlling arm of said cutter-carrying shaft to bear on said mold bar, and means to enable the first rocking member controlled by said volute cam to regulate the position of the second rocking member to guide the cutter in its cutting traverse and means by which the second rocking member can be temporarily freed from the control of the first rocking member and allowed to descend to free the cutting tool from the screw blank during the inoperative retrograde traverse of the cutter and again be controlled by the first rocking member in its subsequent cutting traverse.

5. In a machine for automatically cutting screw threads upon screws which are ta- .pered toward the point, the combination with a jaw carrying spindle, means for opening and closing the jaws carried thereby, a cutter-carrying shaft extending paral lel with and above the said jaw-carrying spindle, means for giving said shaft advance and retrograde endwise motions to out the thread on said screw blank and to return said shaft prior to the next cutting traverse, an arm on said shaft for controlling its angular position about its axis, and a stud on the end of said controlling arm; of a regular cam of volute character, a revoluble shaft to carry said cam, bearings in the framework to carry said shaft, means for giving said cam one revolution during the several traverse motions of the threadcutting tool necessary to complete the formation of the thread, a first rocking frame, a shaft carried by said frame-work upon which said rocking frame is carried, toggle levers connected to said first rocking frame, means for actuating said toggle levers by said volute cum to rock said frame, a second rocking frame, a shaped mold-bar carried thereby upon which the stud. carried by said controlling arm from said cutter-carrying shaft bears, rocking tappetpieces carried by the first rocking frame, studs carried by the second rocking frame with which the tappet pieces of the first rocking frame co-act to communicate the rocking motion of the first rocking frame to the second rocking frame to progressively advance the thread-cutting tool to its work, and means for rocking said tappet pieces of the first rocking frame from beneath said studs of the second rocking frame, to permit the thread-cutting tool to recede from its work during its retrograde movement, and to again place said rocking tappet pieces of the first rocking frame beneath the studs of the second rocking frame to again bring the screw cutting 'tool into operation during its cutting trav erse, substantially as set forth.

6. In a machine for automatically cutting screw threads upon screws which are tapered toward the point; the combination with a rotating jaw-carrying spindle to grip the blank to be operated upon, a cutter-carrying shaft extending parallel with and above the axis of said jaw-carrying spindle, an arm on said cutter-carrying shaft, a cutter carried by said arm to act upon said screw blank carried by said jaws, means for angularly rocking said cutter-carrying shaft about its axis to bring said cutting tool to act on said blank and to cause said cutting tool to produce the taper on said screw blank, and means for rocking said shaft to carry said cutting tool away from said blank; of a sleeve loosely mounted on said cutter-carrying shaft and having a bearing surface, a rotary cam arranged to act on said bearing surface to force said sleeve in the direction of the axis of the shaft, means within the sleeve in operative connection with said cutter-carrying shaft to accelerate the speed of traverse of said shaft during one cutting traverse of said cutter as it nears the point of the blank and to retard the speed of traverse at the next cutting traverse of said shaft as the cutter again nears the point of the blank, and means for giving said cuttercarrying shaft return endwise motions when said cutter is distanced from the work.

7. In a machine for automatically cutting screw threads upon screws which are tapered toward the point; the combination with a rotating jaw-carrying spindle to grip the blank to be operated upon, a cutter-carrying shaft extending parallel with and above the axis of said jaw-carrying spindle, an arm 011 said cutter-carrying shaft, a cutter carried by said arm to act upon said screw blank carried by said jaws, means for angularly rocking said cutter-carrying shaft about its axis to bring said cutting tool to act on said blank and to cause said cutting tool to produce the taper on said means for rocking said shaft to carry said cutting tool away from said blank; of a sleeve loosely mounted on said cutter-carrying shaft and a bearing surface on said sleeve, a rotary cam to act on said bearing surface to force said sleeve in the direction of the axis of said shaft during the forward cutting traverse thereof, a spring to return said shaft in its retrograde inactive traverse,

said cutter-carrying shaft having a recess within said sleeve, a two-armed lever pivoted to said sleeve and located in said recess one arm of said lever acting against the cutter-earrying shaft, a sliding plunger, a bearing in said sleeve to carry said plunger to permit its forward end to contact with the other arm of said pivoted lever carried by said sleeve, a revoluble shaft carried in bearings in the framework, means for driving said shaft, and a cam mounted on said shaft to control the position of said plunger can ried by said sleeve whereby so long as said plunger is permitted to remain stationary by said cam said sleeve and shaft are moved together, while when said plunger is advanced during the cutting traverse of said cuttercarrying shaft, the latter shaft will b ac celerated in its traverse relatively to said sleeve, while when said plunger is permitted to move in the opposite direction said cutter- :arrving shaft will be retarded in its traverse relatively to said sleeve substantiall as-set forth.

In witness whereof I have hereunto set Ill hand in the presence of two witnesses.

\VILLTAM A V Ell Y. \Vitncsses THOMAS W. Roenus, \VILLIAM A. hlansnaipli.

screw blank, and: 

